1. Field of the Invention
The present invention relates to a switch and more particularly to a handle lock device for a switch.
2. Description of the Prior Art
One known prior art handle lock device for a switch is shown in FIGS. 1 to 4, wherein FIG. 1 is a side elevation view of the hitherto used handle lock device for a switch provided with a locking means; FIG. 2 is a plan view of the switch in its assembled state; and FIGS. 3 and 4 are side elevational views, partly broken away, showing the switch in the "on" and "off" states, respectively.
As shown in FIGS. 1 to 4 a handle lock member 1 is provided with a hole 1a adapted to have passed therethrough a shackle part 4a of a padlock 4, and has its lower portion provided with projections 1c and 1c' such that the under surface of handle lock member 1 and the under surfaces both of projections 1c and 1c' lie on an arcuate surface 1b so as to rest on an arcuate surface 3a of a handle 3, whereby the free ends of projections 1c and 1c' act to prevent the lock member 1 from being removed from housing 2.
Handle lock member 1 is mounted, as shown in FIGS. 3 and 4, within an opening 2a of a switch having 2 such that arcuate surface 1b of handle lock member 1 comes into contact with arcuate surface 3a of handle 3, and e.g. as shown in FIG. 3, when switch 2 is in the "on" state, if padlock 4 is inserted into hole 1a of handle lock member 1, the shackle part 4a of padlock 4 acts as a stop to block the movement of handle 3 from the "on" to the "off" position and serves to lock handle 3 in the "on" state. Similarly, FIG. 4 shows that padlock 4 can lock the handle "off". Thus, a single handle lock member 1 can serve to lock handle 3 in either the "on" or the "off" position. Projections 1c and 1c' engage under the edge defining opening 2a to prevent removal of lock member 1.
However, in such a construction there is a limit imposed by the diameter of the shackle 4a of padlock 4 so that not every padlock can be used. Further, padlocks have low reliability and little versatility. Moreover, since handle lock member 1 which is usually formed of metal such as steel plate, stainless steel plate, etc. is mounted within opening 2a of switch 2 with arcuate surface 1b of handle lock member 1 in contact with arcuate surface 3a of handle 3, handle lock member 1 necessarily comes near to a part of a toggle link mechanism (not shown) which is always charged with an electrical potential, so this is not desirable from the view point of safety and electrical insulation.
In order to obviate such a defect a device such as shown in FIGS. 5 to 9 has been proposed, wherein FIG. 5 is a plan of the device, FIG. 6 a partial sectional side elevational view, showing the switch in the "on" state, FIG. 7 is a view similar to FIG. 6, but showing the switch in the "off" state, and FIGS. 8 and 9 are a plan and a sectional side elevational view, respectively, of the essential portion.
It is generally the case that angles .theta..sub.1 and .theta..sub.2 between the axis of a handle 3 and the surface of a switch case 2 in the "on" and "off" positions are not equal. In FIGS. 5 to 9, protruding from switch case 2 molded of insulation material to protect elements contained within it is handle 3 of the switch, and on one surface of handle 3 is provided a groove 3c, and filled with white paint, so as to be visible outside case 2 only when the switch is in the "on" position, whereas when the switch is changed over by movement of the handle 3 to the "off" position, the white line marking groove 3c is concealed within case 2. Thus, the difference between the "on" and "off" positions can be readily discerned. Further, in FIGS. 5 to 9 lock covers 5 and 5' can be mounted on case 2, each having an inclined groove 5a or 5a' therein, and the lower end face 5f or 5f' is adapted to abut one end surface 2b of the frame around the opening in case 2 to lock handle 3 in the "on" or "off" position. In this case, as described above, since it is very rare that .theta..sub.1 is equal or nearly equal to .theta..sub.2, it is necessary to provide two lock covers 5 and 5', respectively, each having an inclined groove 5a or 5a' at a different oblique angle .theta..sub.1 or .theta..sub.2 to accomodate the handle in the respective positions, as shown in FIGS. 6 and 7.
Thus, it will be appreciated that a construction such as shown in FIGS. 5 to 9 can obviate the defects inherent to the construction shown in FIGS. 1 to 4, but the former has another defect, namely that since two kinds of lock covers 5 and 5' have to be provided, it is very troublesome to manipulate and also makes the construction expensive. Further, since lock covers 5 and 5' conceal the white groove 3c in handle 3 as well as the words "on" and "off" marked on case 2, obstructions to the manipulation may be brought about. Moreover, since the upper end face 2b of the frame is utilized the area of the lower end surfaces 5f and 5f' of lock covers 5 and 5' are apt to be larger than the area of the frame of case 2 so that if the switch is to be embedded type or the like, it is very difficult to remove the flush plate with the lock cover in place.
In view of the above defects inherent in the hitherto publicity known handle lock devices for switches, it is a principal object of the present invention to provide a handle lock device for a switch which can overcomes the defects found in the above described conventional types.
It is another object of the present invention to provide a handle lock device for a switch in which a single lock cover makes it possible to carry out the locking action for a switch having a different handle angle in the respective "on" and "off" positions of the switch.
In accordance with the present invention a handle lock device for a switch having a case containing a switching mechanism of the toggle link type and a handle to manipulate the switching mechanism projecting through a handle manipulation opening of the case is provided which comprises a a single-piece cover member of molded insulation material detachably fitted over said handle when said handle is in either of said two extreme positions, said cover member including: (a) a cover portion which closely covers only the portion of the handle which extends outside the opening of the case; and (b) an elongated portion integral with said cover portion and extending generally laterally of said portion and having a size for substantially filling said space which is between the handle and the other end of the opening when the handle is in one of the two extreme positions, thereby preventing the handle from substantially deviating from said one position.
In accordance with one aspect of the present invention the lock cover can cooperate with a detent means which is adapted to secure the lock cover and the handle together, and prevents the former from being separated from the latter when a locking means such as a padlock is used.